Oxford Street-bound … but how do they figure out the numbers? Photograph: Frank Baron for the Guardian

How did London buses get their numbers? Certain numbers used to have digits in common if they were following the same route for a stretch: for example, going to school in London in the 1950s, I could catch the 3 or the 53; my friend could catch the 24 or the 134. Do these kinds of similarities still exist, and how did they come about in the first place?

Sandy Rowntree, Tunbridge Wells, Kent

• Post your answers – and new questions – below or email them to nq@theguardian.com. Please include name, address and phone number